Heterogeneity in the accessory olfactory system

The mammalian accessory olfactory bulb (AOB) is chemoarchitecturally heterogeneous in that it stains differentially with a number of markers; the receptor cells that project to the AOB are similarly heterogeneous. What is the significance of this heterogeneity? We have found that the AOB of the gray, short-tailed opossum, Monodelphis domestica, stains differentially with a number of 'markers': antibodies to olfactory marker protein (OMP) and the alpha subunit of the G protein Gi2, the lectin of Vicia villosa and NADPH-diaphorase. These markers stain the rostral AOB more strongly than the caudal AOB whereas, the G protein subunit G(o) alpha is located predominantly in the posterior subdivision of the AOB. This heterogeneity in the chemoarchitecture of the AOB may reflect a fundamental organizational dichotomy within the vomeronasal system that corresponds to a functional dichotomy. The vomeronasal sensory epithelium also exhibits a chemoarchitectural heterogeneity: receptor cells in the basal third are G(o) alpha-immunoreactive whereas the cells in the middle third are Gi2 alpha-immunoreactive. Tracing studies using WGA-HRP demonstrate that the neurons in the middle third of the vomeronasal sensory epithelium project their axons to the anterior AOB whereas those in the basal third appear to project to the posterior AOB.      

Electrophysiological Correlates of Attentional Disorders in 12- to 13-Year-Old Adolescents

The EEG was recorded in 12- to 13-year-old adolescents with attention deficit hyperactivity disorder (ADHD). During the EEG recording, the subjects performed an attention test. Pairs of tone stimuli in the combinations low–low and low–high were presented in random order with equal probabilities with intervals of 2.3 s. Subjects had to press a button as soon as possible in response to low–low tone pair presentation (a go trial) and not to press the button when a pair consisting of low and high tones was presented (a no-go trial). On the basis of the results of the test performance (the numbers of omissions and false alarms), the subjects were divided into three groups characterized by the degree of severity of the attentional disorder. The evoked potentials in go and no-go trials were detected individually for the subject groups and each derivation. The components N1, N2, P2, P3-go, and P3-no-go were identified in the evoked potentials. These components had different latencies and were differently localized over the head surface. Only the amplitudes of P3-go and P3-no-go in the subjects were statistically significantly correlated with the severity of the attentional disorder.